The present invention relate to Folding Frame Trailers, and, particularly, to folding frame trailers for the logging industry.
In the logging industry, two basic types of trailers are currently used for transporting various forms of round wood. These are frame and pole trailers. The former are designed to support loads at intermediate points between the king pin and the trailer running gear. Therefore, they are extremely versatile--as they can be used to transport any form of round wood: i.e., shortwood, logs, treelengths and full trees. Also, greater payloads are possible due to various loading styles as well as better control over axle weight distribution. Pole trailers have only two bolsters and two sets of standards. The first bolster is usually located over the king pin, approximately just over the midpoint of the tractor tandem. The second bolster is mounted right above the trailer tandem midpoint. A heavy pole connects the trailer upper coupler and the front bolster with the trailer tandem. The whole simplicity of the pole trailer design lies in the fact that the payload's weight is conveyed directly to the road. The pole serves only as a coupling and does not bear any weight of the logs. Consequently, this type of a trailer is about 3,000 pounds lighter than a frame trailer. Therefore, a reduced tare weight can be utilized for an increased payload. Also, there is a proportionally lower purchase investment. However, the practice has demonstrated that pole trailers haul lower average payloads than frame trailers. Also, pole trailers are unable to carry shortwood and logs. The foregoing describes the main reasons for which frame trailers outnumber pole trailers.
Trailers used in the logging industry do not carry any loads during a return trip to the woods. The return ride is very rough on the driver due to less weight on the drive tandem of the truck and large inertia forces exerted on the trailer. Also, trailer off-tracking and its tendency to jack knifing in case of sudden braking contribute to increased driver's fatigue. As a result, folding pole trailers are quite common. Folding pole trailers can be folded and carried on the tractor for the return trip. The advantages include a lower brake and tire maintenance cost, lower fuel consumption, greater maneuverability, and quicker turn-around times. However, recently, the popularity of the folding pole trailer seems to diminish due to an increased perception of the trailer as a dangerous piece of equipment. This stems primarily from allegedly increased number of rear end collisions in which passengers of the other vehicle were killed or severely injured due to an intrusion of the pole into the passengers compartment. In the latest development, state legislatures in some parts of the United States are preparing bills to ban pole log trailers on public roads. An example of this type of folding pole trailer can be seen on U.S. Pat. No. 3,706,464.
U.S. Pat. No. 2,296,858, discloses a folding trailer attached to a truck by a foldable connection adapted to facilitate the loading of the trailer onto the truck.
The folding frame log trailer of the present invention seeks to overcome the foregoing noted disadvantages of the prior art.